Methods and apparatus for reducing crosstalk in electrical connectors

ABSTRACT

A communication jack having crosstalk compensation features for overall crosstalk interference reduction is disclosed. In one embodiment, the jack is configured to receive a plug to form a communication connection, and comprises jack contacts disposed in the jack, with each contact having at least a first surface and a second surface. Upon the plug being received by the jack, the plug contacts interface with the first surface of the jack contacts. The jack further includes a first capacitive coupling connected between two pairs of jack contacts to compensate for near end crosstalk, with the first capacitive coupling being connected to the pairs of jack contacts along the second surface adjacent to where the plug contacts interface with the jack contacts. A far end crosstalk compensation scheme is also set forth.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/055,344, filed Feb. 10, 2005, which issued as U.S. Pat. No. 7,179,131on Feb. 20, 2007 and claims priority to U.S. Provisional ApplicationSer. No. 60/544,050, filed on Feb. 12, 2004; U.S. ProvisionalApplication Ser. No. 60/558,019, filed on Mar. 31, 2004; and U.S.Provisional Application Ser. No. 60/559,867, filed on Apr. 6, 2004; theentireties of which are hereby incorporated by reference. In addition,this application is related in subject matter to U.S. patent applicationSer. No. 11/014,097, filed Dec. 15, 2004 which issued as U.S. Pat. No.7,182,649 on Feb. 27, 2007; and U.S. patent application Ser. No.11/078,816, filed Mar. 11, 2005 which issued as U.S. Pat. No. 7,252,554on Aug. 7, 2007.

TECHNICAL FIELD

The present invention relates to electrical connectors, and moreparticularly, to modular communication connectors that utilizecompensation techniques to reduce net crosstalk generated by thecombination of a plug and a jack of a connector assembly.

BACKGROUND

Computer networks, including local area networks (LAN) and wide areanetworks (WAN), are becoming increasingly prevalent as the number ofcomputers and network devices in the workplace grows. These computernetworks utilize data communication cables and electrical connectors totransmit information between various components attached to the network.The electrical connectors are typically configured to include a plugthat is connectable to a jack mounted in the wall, or integrated into apanel or other telecommunication equipment. The jack typically includesa housing that holds an array of closely spaced parallel contacts forcontacting corresponding conductors of the plug. The contacts of a jackare often mounted onto a printed circuit board. An RJ45 plug and jackconnector assembly is one well known standard connector assembly havingclosely spaced contacts.

Over the past several years, advances in computer networking technologyhave facilitated a corresponding increase in the rate at which data canbe transmitted through a network. Conventional connectors have been usedto transmit low-frequency data signals without any significant crosstalkproblems. However, when such connectors are used to transmithigh-frequency data signals, crosstalk generated within the connectorincreases dramatically. This crosstalk is primarily due to thecapacitive and inductive couplings between the closely spaced parallelconductors within the jack and/or the plug.

A wide variety of improvements have been made in the design ofelectrical connectors to reduce crosstalk occurring within theconnector. One example is disclosed in U.S. Pat. No. 6,305,950, which iscommonly assigned to Panduit Corporation. This type of connector uses aparticular conductor configuration in conjunction with a multi-layeredprinted circuit board containing capacitors to achieve a reduction inthe crosstalk effect. However, due to the high level of crosstalkoccurring in the plug for this connector at very high-frequency signalrates, the tuning effect achievable by the capacitors can still bedifficult to accomplish. As such, further improvements in the design ofconnectors are still needed to address such problems and provideimproved crosstalk performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a connector assembly embodying theprinciples of the present invention;

FIG. 2 is a schematic diagram of the compensation technique to reducecrosstalk in the connector assembly of FIG. 1;

FIG. 3 is a NEXT schematic vector diagram of the connector assembly ofFIG. 1;

FIG. 4 is a FEXT schematic vector diagram of the connector assembly ofFIG. 1;

FIG. 5 is a perspective view of an electrical jack embodying theprinciples of the present invention;

FIG. 6 is an exploded view of the electrical jack of FIG. 5;

FIG. 7 is a sectional view of the electrical jack of FIG. 5 taken alongline A-A of FIG. 5;

FIG. 8 is a plan view of the printed circuit board of the electricaljack of FIG. 5;

FIG. 9 is a plan view of an alternative printed circuit board of theelectrical jack of FIG. 5;

FIG. 10 is a sectional view of the printed circuit board of FIG. 9 takenalong line A-A of FIG. 9;

FIG. 11 is a sectional view of the printed circuit board of FIG. 9 takenalong line B-B of FIG. 9;

FIG. 12 is a perspective exploded view of another electrical jackembodying the principles of the present invention;

FIG. 13 is a sectional view of the electrical jack of FIG. 12 takenalong line B-B of FIG. 12.

FIG. 14 is a perspective view of one embodiment of a flexible circuitcapacitor;

FIG. 15 is a bottom view of the flexible circuit capacitors attached tojack contacts, shown in the unformed state;

FIG. 16 is a top view of the flexible circuit capacitor of FIG. 14;

FIG. 17 is a sectional view taken along line C-C of FIG. 16;

FIG. 18 is a sectional view taken along line D-D of FIG. 16;

FIG. 19 is a sectional view taken along line E-E of FIG. 16;

FIG. 20 is a perspective view of another embodiment of a flexiblecircuit capacitor;

FIG. 21 is a top view of the flexible circuit capacitor of FIG. 20;

FIG. 22 is a sectional view taken along line F-F of FIG. 21;

FIG. 23 is a sectional view taken along line G-G of FIG. 21;

FIG. 24 is a sectional view taken along line H-H of FIG. 21;

FIGS. 25-27 are sectional views taken along lines F-F, G-G and H-H,respectively, of FIG. 21, showing the flexible circuit capacitor beingconnected to a contact;

FIG. 28 is a perspective view of a flexible circuit capacitor accordingto one embodiment of the present invention;

FIG. 29 is a top view of the flexible circuit capacitor of FIG. 28;

FIG. 30 is a sectional view taken along the line I-I of FIG. 29;

FIG. 31 is a sectional view taken along the line J-J of FIG. 29;

FIG. 32 is a sectional view taken along the line K-K of FIG. 29;

FIGS. 33-35 are sectional views of a flexible capacitor showing a solderrivet being attached to a jack contact;

FIG. 36 is a perspective view of a jack contact capacitor according toone embodiment of the present invention;

FIG. 37 is a perspective view of a jack contact capacitor with bentcontact strips;

FIG. 38 is a side view of the jack contact capacitor of FIG. 36;

FIG. 39 is a sectional view taken along the line L-L of FIG. 38;

FIG. 40 is a side cutaway view of the jack contact capacitor of FIG. 36;

FIG. 41 is a side cutaway view showing contact capacitors mounted tojack contacts in a sled in an unmated position;

FIG. 42 is a side cutaway view of the contact capacitors mounted to jackcontacts in a sled of FIG. 41 showing the jack contacts in a matedposition;

FIG. 43 is a perspective view of a jack contact capacitor according toone embodiment of the present invention;

FIG. 44 is a top view of the jack contact capacitor of FIG. 43;

FIG. 45 is a sectional view taken along the line M-M of FIG. 44;

FIG. 46 is a sectional view taken along the line N-N of FIG. 44;

FIG. 47 is a sectional view taken along the line O-O of FIG. 44;

FIG. 48 is a top view of jack contact capacitors attached to jackcontacts;

FIG. 49 is a side view of jack contact capacitors attached to jackcontacts;

FIG. 50 is a rear view of jack contact capacitors attached to jackcontacts;

FIG. 51 is a side cutaway view of jack contact capacitors attached tojack contacts in a sled in an unmated position;

FIG. 52 is a side cutaway view of jack contact capacitors attached tojack contacts in a sled in a mated position;

FIG. 53 a is a perspective view showing jack contact capacitors of oneembodiment of the present invention mounted to jack contacts;

FIG. 53 b is a perspective view showing jack contact capacitorsaccording to one embodiment of the present invention;

FIG. 54 is a detail view of the detail “P” of FIG. 53 b;

FIG. 55 is a side cutaway view showing jack contact capacitors attachedto jack contacts mounted to a sled;

FIG. 56 is a rear view of a jack-and-capacitor assembly according to theembodiment of FIG. 53 a;

FIG. 57 is a side cutaway view of an adhesive area of a jack contactcapacitor connected to a jack contact;

FIG. 58 is a perspective view of a flexible circuit according to oneembodiment of the present invention;

FIG. 59 is a plan view of a flexible shunt according to one embodimentof the present invention;

FIG. 60 is a side view of the flexible shunt of FIG. 59;

FIG. 61 is a side view of a flexible shunt mounted between jack contactsand a printed circuit board;

FIG. 62 is a sectional view taken along the line Q-Q of FIG. 59;

FIG. 63 is a perspective view of flexible circuit capacitors accordingto one embodiment of the present invention;

FIG. 64 is a detail view of the detail “R” of FIG. 63;

FIG. 65 is a top view of a flexible circuit capacitor of FIG. 63;

FIG. 66 is a side view of a flexible circuit capacitor of FIG. 63;

FIG. 67 is a perspective view of a flexible circuit capacitor of FIG. 63attached to jack contacts;

FIG. 68 is a perspective view of the flexible circuit capacitors of FIG.63 attached to jack contacts;

FIG. 69 is a side view of the flexible circuit capacitors of FIG. 63attached to jack contacts;

FIG. 70 is a rear view of the flexible circuit capacitors of FIG. 63attached to jack contacts;

FIG. 71 is an end view showing the overlap of capacitive plates in aflexible circuit capacitor of FIG. 63;

FIG. 72 is a plan view showing the overlap of capacitive plates in aflexible circuit capacitor of FIG. 63;

FIG. 73 is a perspective view of a flexible printed circuit according toone embodiment of the present invention;

FIG. 74 is a plan view of the flexible printed circuit of FIG. 73;

FIG. 75 is a sectional view taken along the line S-S of FIG. 74;

FIG. 76 is a sectional view taken along the line T-T of FIG. 74;

FIGS. 77-80 are plan views respectively showing conductive pathwaysassociated with first, second, third, and fifth conductors of aneight-conductor jack;

FIGS. 81-84 are perspective views progressively showing conductivepathways of the flexible printed circuit of FIG. 73;

FIG. 85 is a perspective view showing a dielectric layer according toone embodiment of the present invention;

FIG. 86 is a plan view showing conductive pathways in the flexibleprinted circuit of FIG. 73;

FIG. 87 is a sectional view taken along the line U-U of FIG. 86;

FIG. 88 is a sectional view taken along the line V-V of FIG. 86;

FIG. 89 is a perspective view of a flexible circuit capacitor accordingto one embodiment of the present invention;

FIG. 90 is a top view of the flexible circuit capacitor of FIG. 89;

FIG. 91 is a sectional view taken along the line W-W of FIG. 90;

FIG. 92 is a sectional view taken along the line X-X of FIG. 90;

FIG. 93 is a sectional view taken along the line Y-Y of FIG. 90;

FIG. 94 is a side view of the flexible circuit capacitor of FIG. 89showing a rivet attached to a jack contact;

FIG. 95 is a side view of the flexible circuit capacitor of FIG. 89showing an adhesive area bonded to a jack contact;

FIG. 96 is a perspective view of a NEXT compensation capacitor circuitaccording to one embodiment of the present invention;

FIG. 97 is a plan view of conductive plates of the NEXT compensationcapacitor circuit of FIG. 96;

FIG. 98 is an end view along the view line “Z” of FIG. 97;

FIGS. 99-104 are plan views of the interior of the NEXT compensationcapacitor circuit of FIG. 96 showing the shapes of conductive plates;

FIG. 105 is a plan view of a flexible printed circuit according to oneembodiment of the present invention;

FIG. 106 is a sectional view taken along the line AA-AA of FIG. 105;

FIGS. 107-109 are perspective views showing successive layers of theflexible printed circuit of FIG. 105;

FIG. 110 is a side cutaway view showing flexible printed circuits ofFIG. 105 installed within a jack with jack contacts in an unmatedposition;

FIG. 111 is a side cutaway view showing flexible printed circuits ofFIG. 105 installed within a jack with jack contacts in a mated position;

FIG. 112 is a plan view of a flexible printed circuit according toanother embodiment of the present invention;

FIG. 113 is a perspective view of a flexible PCB according to oneembodiment of the present invention;

FIG. 114 is a side view of the flexible PCB of FIG. 113;

FIG. 115 is a front view of the flexible PCB of FIG. 113;

FIG. 116 is another front view of the flexible PCB of FIG. 113 showingconductive pathways;

FIG. 117 is an end view toward the line A/A of FIG. 116; and

FIGS. 118-121 are front views of the flexible PCB of FIG. 113 showing,respectively, capacitive plates associated with fifth, third, sixth, andfourth conductors of an eight-conductor jack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the present embodiments in detail, it should beunderstood that the invention is not limited in its application or useto the details of construction and arrangement of parts illustrated inthe accompanying drawings and description. It will be recognized thatthe illustrative embodiments of the invention may be implemented orincorporated in other embodiments, variations and modifications, and maybe practiced or carried out in various ways. Furthermore, unlessotherwise indicated, the terms and expressions employed herein have beenchosen for the purpose of describing the illustrative embodiments of thepresent invention for the convenience of the reader and are not for thepurpose of limitation.

Referring now to the drawings, and more particularly to FIG. 1, acommunication connector assembly 100 is illustrated. The communicationconnector assembly 100 includes a compensation technique that reducesnet crosstalk in accordance with the principles of the presentinvention. As shown in FIG. 1, the communication connector assembly 100includes a plug 102 that is connectable to a jack 104. The jack 104includes a housing 106 and a carrier portion to hold a printed circuitboard (not shown). The housing 106 of the jack 104 holds an array ofclosely spaced parallel contacts for contacting corresponding contactsof the plug 102. When electrical signals are transmitted through thecommunication connector assembly 100, crosstalk occurs within theconnector assembly.

Crosstalk is primarily generated in the connector assembly due to theclosely spaced parallel conductors within the plug 102 and the jack 104.In general, cross-talk is a measure of undesirable signal coupling fromone circuit pair to another. Several different measures of cross-talkhave been developed to address concerns arising in communicationconnector assemblies. Near end crosstalk (NEXT) is a measurement ofcrosstalk traveling in the opposite direction as a disturbing signal ina different circuit pair. NEXT is calculated according to the followingequation: NEXT=Signal Voltage due to (Capacitive Coupling (C)+InductiveCoupling (L)). Far end crosstalk (FEXT) is a measurement of crosstalktraveling in the same direction as a disturbing signal in a differentcircuit pair. FEXT is calculated according to the following equation:FEXT=Signal Voltage due to (Capacitive Coupling (C)−Inductive Coupling(L)). A further description of the principles of crosstalk within aconnector is disclosed in U.S. Pat. No. 5,997,358 (the “358 patent”),which is hereby incorporated by reference.

There is distributed inductive and capacitive coupling between allsignal current carrying conductors in a plug/jack combination from thecable connection to the plug to the cable connection to the jack. Inaddition, there is capacitive coupling between any conductive materialswhich are remote from the above conductors and which are connectedelectrically to the above conductors and between the conductivematerials and the above conductors.

The major couplings which illustrate how a preferred embodimentfunctions are illustrated schematically in FIG. 2:

The plug is primarily distributed inductive and capacitive coupling.

The NEXT compensation zone is remote capacitive coupling.

The jack contacts are primarily distributed inductive and capacitivecoupling.

The NEXT crosstalk zone is remote capacitive coupling.

The FEXT crosstalk zone is a combination of distributed inductive andcapacitive coupling and a remote capacitive coupling.

The distinction between distributed couplings and remote couplings isimportant because of their different effects on NEXT and FEXT.

NEXT is the reflected signal from any coupling back to the cableconnection to the plug. The phase angle of each element of NEXT isdependent on the distance from said cable connection to and from saidelement.

FEXT is the signal from any coupling that travels to the cableconnection to the jack. Thus, all such signals from distributedcouplings are in phase regardless of their location. The phase angle ofthe signal from each remote coupling is, however, dependent on thedistance to and from the remote coupling to the current carryingconductors.

In the illustrated embodiment, conductors 3,6 form one wire pair andconductors 4,5 form another wire pair. It will be recognized thatdifferent wire pair combinations and other wire pairs can be utilizedwithout departing from the spirit and scope of the present invention.

The compensation scheme of the connector assembly 100 includes a NEXTcompensation scheme and a FEXT compensation scheme. The NEXTcompensation scheme preferably includes a NEXT compensation zone and aNEXT crosstalk zone. The NEXT compensation scheme reduces the NEXT ofthe plug and the jack to effectively zero at a selected null frequency.FIG. 3 is a vector representation of the NEXT compensation schemeimplemented on the two wire pairs 3,6 and 4,5 according to the presentinvention.

As shown in FIG. 3, the plug 102 of the connector assembly 100introduces offending NEXT onto the circuit pairs of the connectorassembly 100. The offending NEXT of the plug 102 includes an inductivecomponent from inductive coupling (Lp) and a capacitive component fromcapacitive coupling (Cp). In order to reduce the offending NEXT of theplug 102, the NEXT compensation zone of the connector assembly 100introduces a compensation component from capacitive coupling (C2) on thecircuit pairs of the connector.

The magnitude of the capacitive coupling (C2) is preferably greater thanthe magnitude of the couplings of the plug (Cp+Lp), but with oppositepolarity. In this embodiment, the magnitude of the capacitive coupling(C2) is approximately twice the magnitude of the offending couplings ofthe jack 104. The magnitude of the resultant NEXT is dependent on themagnitude of the phase angle between the coupling of the plug and thecapacitive coupling (C2). The larger the phase angle, the larger theresultant NEXT. It is therefore desirable to minimize this phase angle.This phase angle is proportional to the distance between the effectivecenter of the crosstalk coupling of the plug and the effective center ofthe NEXT compensation zone.

As shown in FIG. 3, the NEXT compensation zone introduces a capacitivecompensation coupling (C2) on the circuit pairs of the jack to reducethe offending NEXT of the plug. As further described below, the NEXTcompensation zone can be implemented in the jack 104 by connectingcapacitors between selected jack contacts at or near but on the oppositesides of the electrical interface 110 of the jack 104 contacts and theplug 102 contacts. As a result, the phase angle between the offendingNEXT of the plug and the compensation component introduced by the NEXTcompensation zone is minimized. The capacitors of the NEXT crosstalkzone are connected between circuit paths 3 and 5, and 4 and 6 at or nearthe electrical interface 110 of the jack contacts and the plug contacts.

Referring again to FIG. 3, the jack contacts of the connector assembly100 introduce couplings onto circuit pairs of the connector assembly.The couplings of the jack contacts include an inductive component (L1)and a capacitive component (C1).

The NEXT crosstalk coupling (C3) has the same polarity as the couplingof the plug 102, but has the opposite polarity of the capacitancecompensation coupling (C2). The NEXT crosstalk zone is located at aparticular phase angle at the null frequency from the NEXT compensationzone. In the preferred embodiment, since the phase angle between thecoupling of the plug and the capacitive coupling (C2) of the NEXTcompensation zone is relatively small, the phase angle between thecapacitive coupling (C2) of the NEXT compensation zone and thecapacitive coupling (C3) of the NEXT crosstalk zone is relatively small.In order to attain a relatively small phase angle between thesecapacitive couplings, the length of that portion of the jack contactsbetween the NEXT compensation zone and the NEXT crosstalk zone isrelatively small. A preferred embodiment disclosed herein minimizes thislength, separates them with air as much as feasible, and still providesadequate force between the jack contacts and the contacts of aninstalled plug.

As shown in FIG. 2, the NEXT crosstalk zone introduces the crosstalkcoupling (C3) on the circuit paths of the connector. The NEXT crosstalkzone is preferably located at a particular phase angle at the nullfrequency from the cable connection to the plug. As further describedbelow, the NEXT crosstalk zone can be implemented in the jack 104, forexample, by connecting capacitors between the input terminals of theprinted circuit board (PCB) of the connector assembly 100. It will alsobe recognized that such capacitors could be connected between thecontacts of the jack 104 at the same locations that the NEXTcompensation zone capacitors are connected. They would, however, beconnected between different conductors to reverse the polarity, and thelength of the electrical conductors from the connection point to theNEXT crosstalk zone capacitors would be larger than the length of theelectrical conductors from the connection point to the NEXT compensationzone capacitors.

The NEXT crosstalk zone capacitors could alternatively be connected tothe jack contacts between the plug/jack contact interface and the cableconnection to the jack. As shown in FIG. 2, the crosstalk coupling (C3)of the NEXT crosstalk zone is introduced by capacitors whose leads areconnected between circuit paths 3, 4 and 5, 6 at the input terminals ofthe PCB.

As further described below, the FEXT crosstalk zone includes a crosstalkcoupling (C_(C)) and compensation couplings (L_(FCZ) and C_(L)). Thelocation of the effective center of the compensation couplings (L_(FCZ)and C_(L)) and the effective center of the crosstalk coupling (C_(C)) ofthe FEXT crosstalk zone are preferably equidistant and equal in phaseangle displacement from the electrical interface of the plug and jack.The NEXT components generated by capacitive coupling in the FEXTcrosstalk zone are generated by C_(C) and C_(L) and the net of thesecouplings is C_(FCZ) which is equal to C_(C)−C_(L). The inductivecompensation coupling in the FEXT crosstalk zone (L_(FCZ)) is preferablyequal in magnitude and of opposite polarity to the crosstalk component(C_(FCZ)). As a result, since NEXT coupling is equal to C+L, the twocomponents (L_(FCZ)) and (C_(FCZ)) will cancel each other out, andtherefore, the FEXT crosstalk zone has little or no effect on NEXT.

Referring to FIG. 4, couplings C and L for a specification plug bothcreate crosstalk which is designated as negative (−).

In this jack design, the jack contacts have couplings C and L which bothcreate crosstalk and which are also negative (−).

As previously stated, NEXT is equal to the signal voltage due tocouplings C+L and FEXT is equal to the signal voltage due to couplingsC−L.

Therefore, the net effect of the couplings due to the plug and the jackcontacts is greatly reduced in their effect on FEXT compared to theireffect on NEXT. Since the combined effects of the various couplings areextremely successful in minimizing NEXT, the same couplings result in anexcessive FEXT.

However, although the net effect of the FEXT crosstalk zone is zero onNEXT, it has a beneficial effect of reducing FEXT.

In the example of the embodiment taught herein, the net capacitivecoupling of the FEXT crosstalk zone is C_(FCZ) and it is crosstalk andhas a negative (−) sign.

The inductive coupling of the FEXT crosstalk zone is L_(FCZ) and it iscompensation and has a positive sign (+).

The couplings that affect NEXT=C_(FCZ)+L_(FCZ)=−0.944 pF+0.948 pF*=0

The couplings that affect FEXT=C_(FCZ)−L_(FCZ)=−0.946 pF−0.946 pF*=1.892pF

*Equivalent pF to nH of L_(FCZ)

The magnitude of the net effect of the FEXT crosstalk zone on FEXT hasbeen derived to be approximately equal to the loss of the net effect ofthe plug and jack contacts on FEXT compared to their effect on NEXT.

In the creation of FEXT, the phase angle displacement between thevarious elements is equal to two times the distance (in Phase AngleDisplacement) from the signal path to the elements. In this embodiment,these phase angles are relatively small, and therefore the FEXT isrelatively small.

The inductive coupling portion of the FEXT crosstalk zone, L_(FCZ) iscreated by adjacent current carrying conductors on the PCB. It is not adesign objective, but these conductors produce a minimal amount ofcapacitive coupling in addition to the inductive coupling. Both of thesecouplings have a polarity which is opposite to that of the couplings inthe plug and which has been designated as positive. The designation ofthis capacitive coupling is C_(L).

The main capacitive coupling portion of the FEXT crosstalk zone iscreated by capacitor plates which are an integral part of the PCB andwhich are connected by conductors to the current carrying conductors inthe above described inductive coupling portion. The connectingconductors are connected at a selected location and are of a selectedlength to insure the phase angle displacement from the plug/jack contactinterface is equal for L_(FCZ) and C_(FCZ). The polarity of thiscapacitive coupling is negative, the same as the couplings in the plug.

The designation of this capacitive coupling is C_(c).

The magnitude of C_(C) is such that C_(C)−C_(L)=C_(FCZ)=Equivalent tomagnitude of L_(FCZ) in pF.

Referring to FIG. 2, FEXT is the signal from any coupling that travelsto the cable connection to the jack. Thus, all such signals fromdistributed couplings are in phase regardless of their location. Thephase angle of the signal from each remote coupling is, however,dependent on the distance to and from the remote coupling to the currentcarrying conductors.

Again, referring to FIG. 4, as compared to FIG. 3, the net plug vectoris reduced in magnitude. The net jack contact vector is reduced inmagnitude. The three components of the FEXT crosstalk zone no longer addup to zero. They are now effective.

Referring to FIG. 4, all the distributed couplings are in phase witheach other and all the remote couplings have a phase angle which islagging the distributed couplings.

The FEXT crosstalk zone can be implemented in the printed circuit boardof the jack by connecting selected magnitudes of capacitance betweencircuit paths and by creating mutual inductance between adjacent circuitpaths. The inductive couplings of the FEXT crosstalk zone are generatedin the printed circuit board by positioning circuit paths 3 and 5 inclose proximity to each other for a selected distance, and positioningcircuit paths 4 and 6 in close proximity to each other for a selecteddistance. As shown in FIG. 8, capacitors are connected between pairs 3,6and 4,5 at a selected distance from the input terminals of the printedcircuit board.

The NEXT generated by the FEXT crosstalk zone is self-canceling asdescribed above. The effects of couplings on FEXT are determined bydistributed couplings and by remote couplings in the same mannerregardless of their positioning along signal paths. Therefore, the FEXTcrosstalk zone can be positioned at any suitable distance from the NEXTcompensation zone, without degrading NEXT or FEXT performance.

The plug is a specification plug which must be used and it containsinductive and capacitive coupling.

The contacts are designed to be short in length and mechanically sound.The result is that they contain inductive and capacitive crosstalkcoupling. Longer and more complicated contacts could be designed to haveminimal inductive coupling or inductive compensation coupling howeversuch complications would not enhance the superior results of thisinvention.

The NEXT compensation zone design provides the minimum phase anglechange from the interface of the plug/jack contacts to the effectivecenter of the NEXT compensation zone. The NEXT compensation zonecoupling is all capacitive because simple alternate designs withinductive coupling would increase the phase angle change. The NEXTcompensation zone design allows minimum NEXT to be achieved and it isone of the most important elements of this invention.

The NEXT crosstalk zone provides only capacitive coupling. This is theoptimum design because it provides the required balance to minimize NEXTand it has no detrimental affect on FEXT.

The results of the above design are:

It provides minimum NEXT; and

It provides relatively large FEXT.

This combination of results creates a problem, however the addition ofthe FEXT crosstalk zone solves this problem because it has no effect onNEXT and has a very beneficial effect on FEXT.

The FEXT crosstalk zone is also one of the most important elements ofthis invention and in combination with the unique compensation zone, thesynergy results in a very important technical achievement.

The parameters of the FEXT crosstalk zone design provided herein resultsin a relatively small FEXT; however, it is contemplated that the FEXTcould be reduced further by changing design parameters.

One example is to increase C_(L) which could be achieved by locatingconductor 3 above 5 instead of adjacent to it and by locating conductor6 above 4 instead of adjacent to it. With C_(L) increased, C_(C) wouldnecessarily be increased. Since the phase angle of C_(C) is more nearly180° from the NEXT compensation zone C2 than C_(C), FEXT would bereduced.

Another example is to increase the length of conductors 3,5 and 4,6 incombination with separating them to keep L_(FCZ) the same. Since C_(C)must be in the center of the FEXT crosstalk zone, the distance from thecurrent paths to the remote C_(C) would necessarily be increased andthis would change its phase angle which could be made optimum.

In one embodiment, the parameters of the components of the compensationscheme implemented by the connector assembly are provided as follows:

Plug:Cp+Lp=Equivalent to −1.472pFCp−Lp=Equivalent to −0.111pF

-   -   where Lp is the inductive coupling of standard plug and Cp is        the capacitive coupling of standard plug.        Jack Contacts:        C1+L1=Equivalent to −0.791pF        C1−L1=Equivalent to −0.071pF    -   where L1 is the inductive coupling of jack contacts and C1 is        the capacitive coupling of jack contacts.        NEXT Compensation Zone:

If the effect of the jack contacts are ignored at 500 MHz nullfrequency, then C2=2.782 pF; however, with adjustments for jackcontacts:C2=3.574pF

-   -   where C2 is the capacitive coupling of NEXT compensation zone.        NEXT Crosstalk Zone:        C3=−1.472pF    -   where C3 is the capacitive coupling of NEXT crosstalk zone.        FEXT Crosstalk Zone:        C_(FCZ)=−0.944pF        −L_(FCZ)=+1.741nH=Equivalent to +0.944pF        C_(C)=−1.138pF        −C_(L)=+0.194pF    -   where: L_(FCZ) is the inductive coupling of FEXT crosstalk zone;        -   C_(FCZ) is the net capacitive coupling of FEXT crosstalk            zone capacitors;        -   C_(FCZ)=C_(C)−C_(L);        -   C_(L) is the capacitive coupling of FEXT crosstalk zone            inductive coupling conductors; and        -   C_(C) is the capacitive coupling of FEXT crosstalk zone            capacitors.

As will be recognized by those skilled in the art, the values of thecomponents of the compensation scheme may be varied in magnitude abouttheir initially determined values for purposes of fine tuning. Althoughthe embodiment has been applied to pairs 3,6 and 4,5 of a connectorassembly, it will be recognized that the principles described herein canbe applied to other pair combinations of an electrical connector, suchas a jack.

Referring now to FIGS. 5-7, an electrical connector implementing acompensation scheme to reduce crosstalk according to the presentinvention is shown. The electrical connector is preferably a jack 200.The jack 200 minimizes the phase angle delay for introducing crosstalkcompensation by introducing it at the plug/jack contact interface wherethe offending crosstalk is introduced to a jack by a mating plug (notshown).

As shown in FIGS. 5-7, the jack 200 includes a housing 202 defining aplug receiving opening 204, a PCB and conductor carrying sled 206 and awire containment cap 208. In the illustrated embodiment, the jack 200 isan 8 contact type (i.e., 4 twisted pair) connector arrangement accordingto a wire pair industry standard (i.e., wires 4 and 5 comprising pair 1,wires 3 and 6 comprising pair 2, wires 1 and 2 comprising pair 3, andwires 7 and 8 comprising pair 4). It is contemplated that the jack canbe any other type of suitable jack or connector.

The contact carrier 206 of the jack 200 includes a printed circuit board(PCB) 210 and a plurality of contacts 220. The contacts 220 each have afirst end portion 222 fixedly attached to the printed circuit board 210and a second free end portion 224. Each contact 220 also has a contactportion 226 extending between its first and second end portions 222,224. When a plug is inserted into the opening 204 of the housing 202,the contact portions 226 of the connector 200 make electrical contactwith the contacts of the plug.

As described above, the plug introduces offending NEXT onto the jackconductors at the electrical interface of the contacts 220 and the plug.As part of the compensation for the offending NEXT of the plug, the jack200 introduces a capacitive compensation coupling (C2) at saidelectrical interface. As shown in FIGS. 6 and 7, the capacitancecompensation coupling (C2) of the NEXT compensation zone is preferablyprovided by flexible printed circuit capacitors 230 and 232 that areconnected with flexible arms to the underside of the contact portions226 of the contacts 220.

In the illustrated embodiment, the capacitors 230 and 232 are connectedacross contacts 220 associated with wire pair 1 (wires 3 and 5) and wirepair 2 (wires 4 and 6). The capacitors 230 and 232 are installed byelectrically connecting flexible printed circuit capacitive plates tothe respective contacts 220. It will be recognized that the capacitorscan be implemented by any suitable capacitive element. Since thecapacitance compensation component (C2) is connected at said plug/jackcontact interface and since the distance from said plug/jack contactinterface to the effective center of the capacitors is minimized, thephase angle between the offending NEXT of the plug and the NEXTcompensation coupling (C2) is minimized.

Referring now to FIG. 8, a preferred layout of the circuit conductors ortraces in the printed circuit board 210 of the jack 200 is shown. Theprinted circuit board 210 has a front portion 250 and a rear portion252. The front portion 250 includes a plurality of front terminals 260labeled 1-8 and the rear portion 252 of the printed circuit board 210includes a plurality of rear terminals 262 labeled 1-8. For explanationpurposes, only the circuit pathways formed between front terminals 260(labeled 3-6) and the rear terminals 262 (labeled 3-6) at the rearportion 252 are shown. Insulation displacement contacts (IDCs) 270 aremounted to each of the rear terminals 262 as shown in FIG. 6. The IDCs270 are electrically connected through the circuit paths on the printedcircuit board 210 to the front terminals 260.

Following the teachings of the '358 patent, the jack 200 introduces acrosstalk or reverse compensation coupling (C3) at specific locations onthe circuit paths of the connector 200 at the NEXT crosstalk zone. Thecapacitance compensation component C3 of the NEXT crosstalk zone of thejack 200 is introduced by capacitors 280 and 282 as shown in FIG. 8.

The capacitors 280 and 282 are connected across front terminals 3, 4 andterminals 5, 6, respectively, of the printed circuit board 210 of thejack 200 and are preferably formed by parallel conductive plates. Itwill be recognized that the capacitors 280 and 282 can be discretecomponents, such as a capacitor, or any other suitable capacitiveelement. For example, the capacitors can be formed on the same ordifferent layers of the circuit board and the shape or type of thecapacitors can be varied.

The printed circuit board 210 of the jack 200 implements a FEXTcrosstalk scheme or zone to reduce or cancel the FEXT of the plug/jackcombination.

The FEXT compensation scheme introduces a crosstalk capacitive coupling(C_(C)) and inductive and capacitive compensation couplings (L_(FCZ) andC_(L)) onto the circuit paths of the printed circuit board 210. Thecapacitance compensation coupling C_(C) of the FEXT crosstalk zone isintroduced by capacitors 290 and 292, and the compensation couplings(L_(FCZ) and C_(L)) are created by positioning the current carryingcircuit paths in close proximity to each other. It is to be noted thatthe thickness or the cross-sectional dimension of the traces as well asthe distance or spacing between the conductors or traces can also beadjusted to achieve the required couplings.

As shown in FIG. 8, the capacitors 290 and 292 are connected acrossterminals 3, 5 and 4, 6, respectively, near the front terminals of theprinted circuit board 210 of the jack 200. Each of capacitors 290 and292 are preferably formed by parallel conductive plates, but can beimplemented by any suitable capacitor element.

The locations of the effective center of the compensation couplings(L_(FCZ) and C_(L)) and the effective center of the capacitancecrosstalk coupling (C_(C)) of the crosstalk zone are preferablyequidistant and equal in phase angle displacement from the electricalinterface of the plug and jack.

It should be noted that the generation of the inductive compensationcoupling (L_(FCZ)) introduces a capacitive coupling (C_(L)) having thesame polarity as the inductive coupling (L_(FCZ)). However, themagnitude of the compensation coupling (C_(C)) is designed to cancel theC_(L) coupling out as well as the inductive coupling (L_(FCZ)) in thegeneration of NEXT. C_(FCZ)=C_(C)−C_(L). As a result, the compensationcouplings (L_(FCZ) and C_(L)) are preferably equal in magnitude and ofopposite polarity to the crosstalk component (C_(C)). Therefore, the twocomponents (L_(FCZ)) and (C_(FCZ)) will cancel each out in thegeneration of NEXT.

The IDCs have been designed so their effect on NEXT and FEXT is minimal.Their effect has been ignored.

The layout illustrated in FIG. 8 is effective in compensating forforward FEXT without adversely affecting forward NEXT (i.e. NEXTobserved when the driven signal is received from the cable connection tothe plug). Because the effective center of the compensation couplings(L_(FCZ) and C_(L)) and the effective center of the capacitancecrosstalk coupling (C_(C)) of the crosstalk zone are designed to beequidistant from the electrical interface of the plug and jack, theresultant inductive and capacitive coupling vectors of the FEXTcrosstalk zone are at the same phase angle location with regard to theireffect on forward NEXT.

For reverse NEXT (i.e. NEXT observed when the driven signal is receivedthrough the IDCs from a cable connection to the end of the jack oppositethe plug), the effective center of the compensation couplings (L_(FCZ)and C_(L)) and the effective center of the capacitance crosstalkcoupling (C_(C)) of the crosstalk zone will not be equidistant from theelectrical interface of the plug and jack. This is due to the physicalasymmetries in the trace layout of FIG. 8, caused by the use of remotecapacitive couplings 290 and 292. As a result, the inductive andcapacitive coupling vectors of the FEXT crosstalk zone will be atdifferent phase angle locations, adversely affecting reverse NEXT.

FIG. 9 is a plan view of a layout for an alternative PCB 550 havingcouplings that are symmetrical from either direction, thereby providingFEXT compensation without adversely affecting forward or reverse NEXT.The PCB 550 includes a front portion 552 and a rear portion 554. Thefront portion 552 includes a plurality of front terminals 560 labeled1-8 and the rear portion 554 includes a plurality of rear terminals 562labeled 1-8. As was the case for FIG. 8, only the circuit pathwaysbetween front terminals (labeled 3-6) and rear terminals (labeled 3-6)are shown. In addition, the NEXT crosstalk zone has been omitted fromFIG. 9 for clarity.

Like the PCB 210 of FIG. 8, the FEXT crosstalk zone of PCB 550 utilizesdistributed inductive couplings (i.e. where traces are placed in closehorizontal or vertical proximity to one another). However, unlike thePCB 210, which used remote capacitive couplings (parallel-platecapacitors 290 and 292), the PCB 550 utilizes distributed capacitivecouplings 590, which take the form of partially overlapping traceswidened to approximate distributed parallel plates. As a result, thecoupling vectors are at the same phase angle location with regard totheir effect on both forward and reverse NEXT. Thus, the FEXTcompensation zone benefits FEXT while being neutral to both forward andreverse NEXT.

FIGS. 10 and 11 are sectional views of the PCB 550 taken along lines A-Aand B-B, respectively, of FIG. 9. The traces corresponding to traces 3,4, 5, and 6 are shown to each traverse one of four internal layers ofthe PCB 550. This stratification provides spacing for desired capacitiveand inductive coupling effects to appropriate FEXT compensation.

While FIGS. 9-11 illustrate one possible implementation of a symmetricalFEXT compensation zone, other implementations may also be used withoutdeparting from the intended scope of the invention. For example,different lengths and arrangements of traces may be used. Similarly,different shapes and configurations for distributed capacitances may beadopted.

Referring now to FIGS. 12 and 13, another electrical connector 300implementing the same compensation scheme to reduce NEXT and FEXTaccording to the present invention is shown. The electrical connector300 is substantially similar to the previously described electricalconnector 200, except that the connection arrangement between the jackand the cable to which it is connected is a “punch down” design.Components of the electrical connector 300 which generally correspond tothose components of the electrical connector 200 of FIG. 5 aredesignated in the three-hundred series. As such, further description ofthe electrical connector 300 is unnecessary for a complete understandingof the present invention.

The method and apparatus of the present invention provide a compensationtechnique to cancel or reduce the NEXT and FEXT produced by theelectrical connector. In particular, the compensation scheme introducescompensation and crosstalk couplings into the electrical paths of theelectrical connector to reduce or cancel the net crosstalk generated bythe plug/jack combination.

In the illustrated embodiment, the capacitors 230 and 232 are connectedacross contacts 220 associated with wire pair 1 (wires 3 and 5) and wirepair 2 (wires 4 and 6). The capacitors 230 and 232 are installed byelectrically connecting flexible printed circuit capacitive plates tothe respective contacts 220. It will be recognized that the capacitorscan be implemented by any suitable capacitive element. Since thecapacitance compensation component (C₂) is connected at said interfaceand since the distance from said interface to the effective center ofthe capacitors is minimized, the phase angle between the offending NEXTof the plug and the NEXT compensation coupling (C₂) is minimized.

FIGS. 14-19 illustrate one embodiment of the flexible printed circuitcapacitors. These flexible circuit capacitors are made, for example,from a plated film of KAPTON® polyimide film manufactured by DuPont. Thecapacitors 230 and 232 include a pair of dome-shaped rivets and areattached opposite the plug/jack contact interface via electricalresistance or spot welding.

FIGS. 20-27 illustrate a second embodiment of the flexible printedcircuit capacitors 230 and 232. These capacitors include a solder “plug”236 and are attached to the contacts 220 that may include a pre-tinnedarea 238.

FIGS. 28-121 illustrate additional embodiments of capacitors accordingto the present invention. FIG. 28 shows a flexible circuit capacitor 400having solder rivets 402. The solder rivets 402 are pre-formed andmechanically deformed into holes provided at the ends of the capacitor400. The flexible circuit capacitor 400 attaches to jack contacts by aresistance weld process. FIG. 29 is a top view of the flexible circuitcapacitor 400, and FIGS. 30, 31, and 32 are, respectively,cross-sectional views taken along the lines I-I, J-J, and K-K of FIG.29. As shown in FIG. 30, the solder rivet 402 is inserted in a platedthrough hole 404. The plated through hole 404 is provided with pads. Therivet 402 has a dome head 406 (shown in FIG. 31), and the rivet 402 ismechanically deformed on the underside as shown in FIGS. 30 and 32.

FIGS. 33, 34, and 35 are cross-sectional views of a flexible circuitcapacitor 400 with a solder rivet 402 being attached to a jack contact408. As shown in FIG. 33, the jack contact 408 may be provided with apre-tinned region 410 tinned with solder. The flexible circuit capacitor400 is brought together with the jack contact 408 as shown in FIG. 34 sothat the solder rivet 402 makes physical contact with the pre-tinnedregion 410. Then, as shown in FIG. 35, a welding tool 412 welds therivet 402 to the contact 408, for example by resistance welding. Thewelding may be performed simultaneously on several rivet-contactinterfaces. The centerline 412 c shown in FIG. 35 is preferably locatedat the plug/jack contact interface.

FIG. 36 shows an alternative PCB-type jack contact capacitor 413. Thejack contact capacitor 413 can serve as a NEXT compensation zone. Inthis embodiment, a printed circuit board 414 has contact strips 416attached to it at eyelets 418. Contact mating areas 420 are alsoprovided on the contact strips 416 for attachment, for example viawelding, to contacts of a jack. A similar construction is shown in FIG.37, with the contact strips 416 bent for alternative mounting of thecontact capacitor to a contact. FIG. 38 is a side view of the jackcontact capacitor 413 of FIG. 36, and FIG. 39 is a cross-sectional viewtaken along the line L-L of FIG. 38.

The cross-sectional view of FIG. 39 shows the contact strip 416 held inplace by the eyelet 418 and in electrical contact with a plated throughhole 422. Conductors 424 are also in contact with the plated throughhole 422 and allow capacitive coupling between contact strips 416 withina printed circuit board 414. FIG. 40 shows a side cutaway viewillustrating varying widths of the conductors 424 within the printedcircuit board 414.

FIGS. 41 and 42 are side views of contact capacitors mounted to jackcontacts 408 provided in a sled 426. The printed circuit boards 414 ofthe jack contact capacitors fit within capacitor guides 428 of the sled426. A sled-mounted printed circuit board 430 may be provided within thesled 426. FIG. 41 shows the jack contacts 408 not mated to a plug andFIG. 42 shows the jack contacts 408 bent downwardly as they would bebent when mated to a plug. A centerline 430 c shows the plug/jackcontact interface. The contact strips 416 are welded to the contacts 408directly beneath the plug/jack contact interface, along the centerline430 c.

Turning now to FIG. 43, another embodiment of a jack contact capacitor432 for implementing a NEXT compensation zone is shown. In theembodiment of FIG. 43, a flexible printed circuit 434 is adapted forconnection to jack contacts via rivets 436 a and 436 b. The rivets 436 aand 436 b are preferably provided with domed heads. FIG. 44 is a topview of the jack contact capacitor 432, and FIGS. 45-47 are,respectively, cross-sectional views taken along the lines M-M, N-N, andO-O of FIG. 44. As shown in FIG. 45, a plated through hole 438 allowsfor electrical connection between a first rivet 436 a and a firstconductive plate 440. Further, as shown in FIG. 47, another platedthrough hole 438 allows for electrical connection between a second rivet436 b and a second conductive plate 442. FIG. 46 shows a cross-sectionalview of a region of capacitive coupling between the first conductiveplate 440 and the second conductive plate 442.

FIGS. 48-50 show jack contact capacitors 432 a and 432 b attached tojack contacts 408. FIG. 48 is a top view of jack contacts 408 attachedto jack contact capacitors 432 a and 432 b, and FIG. 49 is a side viewof the assembly of FIG. 48 and FIG. 50 is a rear view of the assembly ofFIG. 48. Contacts 3, 4, 5, and 6 of an eight-contact jack are shown. Acenterline 442 c of the welding between the jack contacts 408 and thejack contact capacitors 432 a and 432 b aligns with a plug/jack contactinterface. The jack contact capacitors 432 a and 432 b are welded to thejack contacts 408 at a side opposite the plug/jack contact interface.Jack contact capacitors 432 a and 432 b can be attached to jack contacts408 and mounted within a sled 426 as shown in FIGS. 51 and 52. FIG. 51shows the position of jack contacts 408 when a plug is not mated to thejack contacts 408 and FIG. 52 shows the position of jack contacts matedwith a plug. A printed circuit board 430 may be provided within the sled426. Capacitor guides 428 are positioned to accept the jack contactcapacitors 432 a and 432 b.

Another embodiment of a jack contact capacitor is shown in FIGS. 53a-56. According to this embodiment of the present invention, jackcontact capacitors 444 a and 444 b are adhesively mounted to jackcontacts 408. FIG. 53 a shows jack contact capacitors 444 a and 444 bmounted to jack contacts 408. Jack contacts 3, 4, 5, and 6 of aneight-contact jack are shown. FIG. 53 b shows the jack contactcapacitors 444 a and 444 b separated from the jack contacts 408, andFIG. 54 is a detail view of the detail “P” of FIG. 53 b. As shown inFIG. 54, adhesive areas 446 are provided on contact strips 416 of thejack contact capacitors 444 a and 444 b. The adhesive areas 446 allowfor an adhesive connection to be made between the jack contactcapacitors 444 a and 444 b and the jack contacts 408. The resultingassembly can be mounted on a sled 426 as shown in FIG. 55, withcapacitor guides 428 accepting the jack contact capacitors 444 a and 444b. The adhesive areas 446 are located directly beneath a plug/jackcontact interface. FIG. 56 is a rear view of a jack-and-capacitorassembly according to this embodiment of the invention.

According to one embodiment, the jack contact capacitors 444 a and 444 bare formed with flexible printed circuits 448, as shown in FIG. 54. FIG.57 shows a side cutaway view of an adhesive area 446 of a jack contactcapacitor 444 connected to a jack contact 408. Adhesive 450 is placedbetween a first dielectric layer 452, such as a layer of MYLAR® PET filmmanufactured by DuPont, and a jack contact 408. A conductor pattern 454is layered between the first dielectric layer 452 and a seconddielectric layer 456. The conductor pattern 454 is layered between thefirst and second dielectric layers 452 and 456 in a flexible printedcircuit 448. The jack contact capacitors 444 a and 444 b are adhesivelybonded to alternate jack contacts. For example, jack contact capacitor444 a may be bonded to jack contact pair 3-5 and jack contact capacitor444 b may be bonded to jack contact pair 4-6. This construction createsa capacitor by means of the conductor material 454 in the laminate formand the contact 408 itself. Two contacts are then coupled by twocapacitors in series. Total capacitance between contacts is ½ the valueof each capacitor. The thickness and dielectric constant of the adhesiveare included in the calculations.

FIGS. 58-61 show a NEXT compensation zone and flexible circuit contactshunt according to one embodiment of the present invention. A flexibleNEXT compensation circuit 458 comprises a capacitor flexible circuit 460adapted to connect to jack contacts via contact weld rivets 462 andfurther adapted to make electrical contact with a printed circuit boardvia printed-circuit-board compliant pins 464. In the embodiment shown inFIG. 58, capacitive coupling between two contacts may be accomplishedwithin a capacitor flexible circuit 460. Turning to FIG. 59, a flexibleshunt 466 is shown. The flexible shunt 466 is provided with rivets 462on flexible members 463 for connection to jack contacts and withPCB-compliant pins 464 for connection to a printed circuit board. A sideview of the flexible shunt 466 is shown in FIG. 60. FIG. 61 is a sideview illustrating the placement of a flexible shunt 466 between jackcontacts 468 and a printed circuit board 470. A segment of a plug 471 isshown, and the plug/jack contact interface 473 is directly above thelocation of attachment of the rivets 462 to the jack contacts 468. FIG.62 is a cross-sectional view of the flexible shunt 466 along the lineQ-Q of FIG. 59. A conductive trace 472, such as a copper trace, issurrounded by a dielectric 474 such as KAPTON® polyimide filmmanufactured by DuPont. The use of a flexible circuit shunt 466 shortensthe current path from the plug 471 to the PCB 470. FIGS. 59-62 show aflexible shunt 466 providing electrical connection only, with nocapacitor plates. The use of a flexible circuit shortens the currentpath from the plug 471 to the printed circuit board 470. For example,the signal length x₂ shown in FIG. 61 is less than the signal length x₁.

FIGS. 63-72 show an alternative flexible circuit capacitor 476 forimplementing a NEXT compensation zone. FIG. 63 is a perspective view oftwo flexible circuit capacitors 476 a and 476 b having domed rivets 478for attachment to first through eighth jack contacts as labeled in FIG.63. FIG. 64 is a detail view of the detail “R” of FIG. 63 showing adomed rivet 478 adapted for welded attachment to a jack contact and aplated through hole 480 for establishing electrical connection between ajack contact and capacitive plates 482, shown as dotted lines in FIG.63. FIG. 65 is a top view of the flexible circuit capacitor 476 moreclearly showing the arrangement of the capacitive plates 482 and FIG. 65is a side view of the flexible circuit capacitor 476, showing a 90° bend475.

FIG. 67 is a perspective view showing a flexible circuit capacitor 476 aattached to four jack contacts 484. FIG. 68 is another perspective view,showing an additional flexible circuit capacitor 476 b attached to theother four jack contacts 484. The two flexible circuit capacitors 476 aand 476 b partially overlap each other. FIGS. 69 and 70 are respectivelyside and rear views showing the flexible circuit capacitors 476 a and476 b attached to the jack contacts 484. A first flexible circuitcapacitor 476 a is attached to first, second, third, and fifth jackcontacts 484, and a second flexible circuit capacitor 476 b is attachedto fourth, sixth, seventh, and eighth jack contacts 484 as shown inFIGS. 68 and 70.

The overlap of capacitive plates within a flexible circuit capacitor 476is shown in FIGS. 71 and 72. FIGS. 71 and 72 show the flexible circuitcapacitor for connection to first, second, third, and fifth jackcontacts; the capacitors connected to eighth, seventh, sixth, and fourthcontacts are a mirror image of the illustrated capacitors. All paircombinations except for 1,2-7,8 are included. The flexible circuitcapacitors 476 a and 476 b are welded to the bottom of jack contactsdirectly below the plug/jack contact interface.

Turning now to FIGS. 73-88, a flexible printed circuit 486 with acapacitive and inductive NEXT compensation zone is shown. FIG. 73 is aperspective view of a flexible printed circuit 486 with rivets 488 forconnection to jack contacts and printed-circuit-board compliant pins 464for connection to a printed circuit board. The flexible printed circuit486 can flex between jack contacts and a printed circuit board when aplug is mated to jack contacts, and the rivets 488 are welded directlybeneath a plug/jack contact interface. FIG. 74 is a plan view of aflexible printed circuit 486 showing conductive pathways 490 with dottedlines. A flexible printed circuit 486 for providing a NEXT compensationzone for conductors 1, 2, 3, and 5 is shown; a flexible printed circuitfor providing a NEXT compensation zone for conductors 4, 6, 7, and 8 isa mirror image of the shown flexible printed circuit 486. Conductivepathways 490 are provided within the flexible printed circuit 486 suchthat the flexible printed circuit 486 provides both capacitive andinductive NEXT compensation on all conductor pairs except 1,2-7,8.

FIG. 75 is a cross-sectional view along the line S-S of FIG. 74 and FIG.76 is a cross-sectional view along the line T-T of FIG. 74. These viewsshow the positioning of conductive pathways 490 along first and secondcross-sections of the flexible printed circuit 486.

FIGS. 77-80 are plan views respectively showing in solid lines theconductive pathways 490 a-490 d associated with first, second, third,and fifth conductors of an eight-conductor jack.

FIGS. 81-84 progressively show conductive pathways 490 of the flexibleprinted circuit 486 as printed on the flexible printed circuit 486 fromthe lowermost to the uppermost conductive pathway. FIG. 81 shows thelowermost conductive pathway 490 b associated with the second conductor.FIG. 82 shows the second lowermost conductive pathway 490 d associatedwith the fifth conductor. FIG. 83 shows the second uppermost conductivepathway 490 c associated with the third conductor. FIG. 84 shows theuppermost conductive pathway 490 a associated with the first conductor.FIG. 85 shows a dielectric layer 474 such as a layer of Kapton polyimidefilm manufactured by DuPont. The flexible circuit 486 is formed byoverlapping these layers.

FIG. 86 is another plan view of the conductive pathways 490 a-490 d, andFIGS. 87 and 88 are respectively cutaway views along the lines U-U andV-V of FIG. 86 showing the overlapping of the conductive pathways 490a-d. Capacitive plates for the first conductor adjacent capacitiveplates for the third conductor and capacitive plates for the secondconductor adjacent capacitive plates for the fifth conductor may beadded as required.

Flexible circuit boards according to some embodiments of the presentinvention may be attached to jack contacts using more than one method ofattachment. FIG. 89 is a perspective view of a flexible circuitcapacitor 492 adapted for both welding and adhesive attachment to jackcontacts. A rivet 488 is provided for attachment to one jack contact andan adhesive area 446 is provided for attachment to another jack contact.FIG. 90 is a top view of the flexible circuit capacitor 492, and FIGS.91-93 are, respectively, cross-sectional views of the flexible circuitcapacitor 492 taken along the lines W-W, X-X, and Y-Y of FIG. 90. Aflexible dielectric material 494 overlays first and second conductiveplates 440 and 442. The adhesive area 446 is shown in FIG. 91 and arivet 488 extends through a plated through hole 489 as shown in FIG. 93.FIG. 94 is a side view showing the rivet 488 welded to a jack contact408 and FIG. 95 is a side view of the adhesive area 446 bonded to a jackcontact 408. As described above, capacitive coupling between the jackcontact 408 and the flexible circuit capacitor 492 occurs at theadhesive bond area. Both the weld and the adhesive bond are placeddirectly beneath a plug/jack contact interface.

Turning now to FIGS. 96-104, a NEXT compensation capacitor circuit 496for connection to all eight conductors of an eight-conductor jack isillustrated. The NEXT compensation capacitor circuit 496 is a flexiblecapacitor circuit. FIG. 96 is a perspective view of a NEXT compensationcapacitor circuit 496. Rivets 497 are provided for welding to thebottoms of jack contacts at plug/jack contact interfaces. FIG. 97 is aplan view of conductive plates 498 associated with each of the eightcontacts of a jack. The association between conductive plates 498 a-498h with the respective first through eighth contacts is shown in FIG. 98,which is a side view along the view line Z of FIG. 97 showing theoverlap of the conductive plates 498 a-498 h.

FIGS. 99-104 are plan views of the interior of the NEXT compensationcapacitor circuit 496 showing the shapes of conductive plates 498 a-498h. FIGS. 99-104 progress from FIG. 99 which shows the lowermostconductive plate 498 a of FIG. 98 (associated with a first jack contact)to FIG. 104 which shows the uppermost conductive plate 498 h of FIG. 98(associated with an eighth jack contact).

FIGS. 105-109 illustrate another flexible printed circuit 500 withcapacitive and inductive NEXT compensation for attachment to contacts ofa jack. FIG. 105 is a plan view of the flexible printed circuit 500 withdotted lines showing conductive pathways 502. A first end 504 of theflexible printed circuit 500 is attached to jack contacts viaweld/solder pads 505 provided on flexible members 507 and a second end506 is attached to a printed circuit board via PCB-compliant pins 464.The flexible printed circuit 500 is adapted for use with third and fifthcontacts of an eight-contact jack; an identical flexible printed circuit500 can also be used with fourth and sixth contacts.

FIGS. 107-109 show successive layers of the flexible printed circuit500. FIG. 107 shows a first dielectric layer 508 a and a firstconductive pathway 502 a associated with a third jack contact. FIG. 108shows a second dielectric layer 508 b and a second conductive pathway502 b associated with a fifth jack contact. FIG. 109 shows a thirddielectric layer 508 c. The dielectric layers 508 a-c may be comprisedof KAPTON®.

FIGS. 110 and 111 show flexible printed circuits 500 installed within ajack. Jack contacts 408 are mounted within a sled 426 and the flexibleprinted circuits 500 are welded to the jack contacts 408 beneath aplug/jack contact interface. The flexible printed circuits 500 aresoldered to a PCB 509. FIG. 110 shows the jack contacts 408 in aposition in which they are not mated to a plug and FIG. 111 shows thejack contacts 408 in a position in which they are mated to a plug. Theflexible printed circuits 500 flex as the jack contacts 408 move betweenthe two positions. The arrows of FIG. 111 show a current path throughthe jack including the paths through the flexible printed circuits 500.

FIG. 112 is a plan view of another flexible printed circuit 510 forproviding capacitive and inductive NEXT compensation. Rivets 511 areprovided for attachment to jack contacts. The flexible printed circuit510 of FIG. 112 is adapted for attachment to third and fifth jackcontacts, but a substantially identical flexible printed circuit can beused for attachment to fourth and sixth jack contacts of aneight-contact jack. Conductive pathways 512 a and 512 b are providedwithin the flexible printed circuit 510, and capacitor plates 514 a and514 b are attached to each of the conductive pathways 512 a and 512 b.The vertical runs of the conductive pathways 512 a and 512 b areparallel but not collinear. Inductive segments 516 a and 516 b make up aportion of the vertical runs. The inductive segments 516 a and 516 b areadjacent current carrying conductors and/or transformers providinginductive compensation coupling.

FIG. 113 is an upper right-side perspective view, FIG. 114 is a sideview, and FIG. 115 is a front elevational view of one embodiment of aflexible PCB 518 that may be utilized in accordance with the presentinvention to provide crosstalk compensation. The PCB 518 includes a mainportion 520 and attachment fingers, such as the finger 522. The mainportion 520 supports a plurality of capacitive plates (in this case,four plates, corresponding to plug interface contacts 3-6) to providecapacitive coupling. As will be illustrated in FIGS. 116-121, the leadsto the capacitive plates provide an inductive coupling component aswell. The fingers 522 serve as an attachment mechanism for attaching thePCB 518 to the plug interface contacts. While any suitable attachmenttechnique may be used, in the illustrated embodiment, a resistance weldrivet 524 is used. In addition to attaching the PCB 518 to the pluginterface contacts (or another conductor connected to the plug interfacecontacts), the rivet 524 acts as a contact post for the capacitiveplates and their leads. This is illustrated in FIGS. 114-121, which showfour layers of capacitive plates 526 and leads (528 a-d), through whichthe rivet 524 protrudes to make appropriate contact in the fingers 522.

FIG. 116 is a front elevational view of the PCB 518 with the fingers inan unbent configuration, for ease of illustration. FIG. 117 is across-sectional view of the capacitive plates and leads as viewed upwardfrom the bottom of the PCB 518 toward line A/A in FIG. 116. Note thatFIG. 114 does not show portions of the PCB 518 that merely support thecapacitive plates and leads or serve as a dielectric or insulator. FIGS.116-121 show how the capacitive plates and leads are placed with respectto one another to result in a relatively high density of inductivecoupling in a relatively short distance. For example, in FIG. 116, thecapacitive plate 526 a and lead 528 a for conductor 5 is the topmostplate and lead shown, having a sideways “U” shape. The same “U” shape,but with varying orientation, is used for conductors 3, 4, and 6, asshown by the dashed and solid lines of FIG. 116. The physical placementand overlapping area of the capacitive plates determines the amount ofcapacitive coupling. Similarly, the separation of the leads from oneanother and the length of overlap determine the amount of inductivecoupling. FIG. 117 also illustrates the relative direction of currentflow due to inductive couplings in the respective leads, which providesa high density of inductive coupling. FIGS. 118-121 show, respectively,leads 528 a-d and capacitive plates 526 a-d associated with,respectively, fifth, third, sixth, and fourth conductors of aneight-conductor jack.

While the particular preferred embodiments of the present invention havebeen shown and described, it will be obvious to those skilled in the artthat changes and modifications may be made without departing from theteachings of our invention. The matter set forth in the foregoingdescription and accompanying drawings is offered by way of illustrationonly and not as a limitation. The actual scope of the invention isintended to be defined in the following claims when viewed in theirproper perspective based on the prior art.

1. A crosstalk compensation apparatus for a jack/plug combination whichincludes a Far End Crosstalk (FEXT) crosstalk zone, a net inductivecoupling in the FEXT crosstalk zone being approximately equal inmagnitude and of opposite polarity to a net capacitive coupling in theFEXT crosstalk zone wherein the net capacitive coupling of the FEXTcrosstalk zone is of the same polarity as the net capacitance associatedwith the plug.
 2. The crosstalk compensation apparatus of claim 1,wherein the net capacitive coupling comprises a distributed capacitivecoupling and a remote capacitive coupling.
 3. The crosstalk compensationapparatus of claim 1, wherein the FEXT crosstalk zone is symmetric withrespect to conductors connected directly to the plug and conductorsconnected directly to the jack.
 4. The crosstalk compensation apparatusof claim 2, wherein the net inductive coupling comprises distributedinductive coupling.
 5. The crosstalk compensation apparatus of claim 2,wherein the net inductive coupling consists of distributed inductivecoupling, and the net capacitive coupling is equal to the remotecapacitive coupling minus the distributed capacitive coupling.
 6. Acrosstalk compensation apparatus for a jack/plug combination whichincludes a Far End Crosstalk (FEXT) crosstalk zone, net inductive andcapacitive couplings in the FEXT crosstalk zone being approximatelyequal in magnitude and of opposite polarity, wherein the phase angledisplacement from a plug/jack interface to the net inductive coupling ofthe FEXT crosstalk zone is approximately equal to the phase angledisplacement from the plug/jack interface to the net capacitive couplingof the FEXT crosstalk zone.
 7. A crosstalk compensation apparatus for alack/plug combination which includes a Far End Crosstalk (FEXT)crosstalk zone, net inductive and capacitive couplings in the FEXTcrosstalk zone being approximately equal in magnitude and of oppositepolarity, wherein the FEXT crosstalk zone is symmetric with respect toconductors connected directly to the plug and conductors connecteddirectly to the jack, and the inductive and capacitive couplingsminimize the FEXT crosstalk zone effect on forward and reverse Near EndCrosstalk (NEXT).